Method for dyeing polyester fibers with monoazo dyestuffs



United States Patent ABSTRACT OF THE DISCLOSURE Polyester fiber is dyedby padding with a dye of the formula:

at a temperature of from 140 F. to 180 F., then drying and heating thedried material to a temperature of from 390 F. to 440 F. for one-half totwo minutes.

The present invention relates, in general, to the art of dyeingsynthetic materials and, in particular, to an improved method of dyeinga polyester fiber utilizing an azo dye of the formula:

With the advent of synthetic fibers as textile materials andparticularly polyester-type materials the demand for improved dyeingprocesses'for these materials has increased. Similarly, conventionaldyes, of the type previously found suitable for dyeing other syntheticfibers such as polyamides and acetates, when employed in the dyeing ofpolyester-type materials, have been found unsatisfactory since thesedyes lack sufiicient wash and dry cleaning fastness and are notsufficiently resistant to fading and sublimation. Etforts to overcomethese drawbacks have led to the development of processes employing atype of dye wherein diazotiza-tion and coupling occur directly upon thefiber. While this expedient has offered some irnprovements, suchprocesses are quite diificult and lengthy. Additionally, many new dyeshave been olfered on the market which have been particularly tailoredfor use in dyeing polyester fibers, however, many of these dyes whenapplied to polyester fibers result in products of poor light fastnessand when the dyes are of sufficient light fastness they are usuallysubject to the disadvantage of insufi'icient resistance to sublimationat high temperatures thus preventing their use in high temperaturedyeing processes which are presently commercially advantageous inproducing especially fast, bright dyeings in an economical and practicalmanner.

Accordingly, it is a primary object of this invention to overcome theaforementioned and other difficulties by means of an improved method fordyeing a polyester material.

Another object of this invention resides in the provision of a methodwhich provides improved dyeings characterized by superior light, washand dry-cleaning fastness.

Still another object of this invention resides in the provision of animproved process for dyeing a polyester fiber at high temperatureswherein the dye employed is characterized by good resistance tosublimation under the dyeing conditions.

Yet another object of this invention resides in the provision of meansfor dyeing a polyester fiber a strong bright orange color of goodbuild-up with fastness to light, washing, dry cleaning, crocking andsublimation.

These and other objects, features and advantages of the presentinvention will become further apparent as the detailed description ofthe invention proceeds.

The achievement of the aforesaid objects of the invention is readilyaccomplished by the method which comprises impregnating a polyesterfiber at a first elevated temperature with an aqueous dispersion of anazo dye of the formula:

drying said dyed polyester fiber and subsequently subjecting said driedfiber to a second elevated temperature higher than said first elevatedtemperature for a period of time sufiicient to develop the full color ofsaid dyed polyester fiber.

The term a polyester fiber as used herein is intended to include thefibers obtained by the polyester condensation products of dicarboxylicacids and polyols and in particular those polyesters obtained by thecondensation of terephthalic acid and ethylene glycol as well as mixedpolyesters and blends thereof with other synthetic and/or naturallyderived fibers such as cotton. The invention is also applicable topolyester fibers which have been modified or plasticized by the additionof other materials such as glycols or plasticizers which are mixed withthe polyethylene terephthalate.

The azo dyestufi' represented by .the above formula is readily preparedby diazotization of 6-chloro-alpha, alpha,alpha-trifiuoro-meta-toluidine and subsequently coupled with a NaphtholAS compound of the formula:

OH CH3 condensation of sulphonated aromatic derivatives with aldehydes,such as the methylene-dinaphthylsulphonates, are particularly valuableauxiliary substances since they allow the preparation of a gooddispersion of the dyestuffs and facilitate the taking up of the latteron the polyester fibers. On the other hand, carriers, such as monoorpoly-chlorinated derivatives of the benzene series or diphenyl, can beadded to the dye bath or to the printing pastes. These substances exerta swelling action on the polyester fibers and are capable of improvingthe t-inctorial yield.

'In carrying out the dyeing procedure of the present invention weightpercent active dispersed paste of the dyestutf is dissolved in water atconcentrations of from about 1.0 to 15.0 ounces per gallon. The solutionis thickened to suitable padding consistency by the addition ofconventional thickeners such as gum traga-canth in quantities normallyabout twice that of the water employed.

The dyeing method of the invention comprises essentially impregnatingthe polyester fiber by padding or printing with an aqueous suspension orsolution of the dye corresponding to Formula 1 above at a temperature ofabout 140 F. to 180 F., drying the impregnated fiber and subsequentlysubjecting said impregnated fiber to a heat treatment at a temperatureof from about 390 F. to about 440 F. for a period of time sufficient todevelop the full color.

The aforesaid procedure results in polyester dyeings of a strong, brightorange color of excellent build-up with an unexpected fastness to light,washing and dry cleaning, crocking and sublimation.

That such results are obtained is indeed surprising since inferiorresults are obtained by dyeing other synthetic tfibers with the dyestutiof the invention and, on the other hand, equally inferior results areobtained by dyeing polyester fiber with dye compounds of a structuresimilar to the dyestuff of this invention. Thus, it appears that theunexpected results obtained are primarily due to the unique combinationof the polyester fiber and the dyestutf of the invention.

The commercial significance of the instant invention resides, in part,in the fact that the Thermosol dyeing of polyester fibers has proven tobe a persistent problem particularly with respect to producing dyedfibers in the yellow and orange shade ranges because most yellow andorange dyes heretofore employed in the Thermosol process sublimed orvolatilized during processing thus smearing not only the goods but theequipment.

The following example will serve to illustrate the practice of theinvention:

Example 1 To 268 pounds of hydrochloric acid 20 B. there were added 44.1pounds of 6-chloro-alpha, alpha, alpha-tritfiuoro-m-toluidine. Afterstirring Well, 150 pounds of ice was added followed by the addition of17.1 pounds of a 31.5% sodium nitrite solution and the mixture stirredfor one hour. It was then treated with 2 pounds of diatomaceous earthand 0.5 pound of activated carbon and 'rfiltered. Before coupling anadditional 250 pounds of ice was added and excess nitrite removed withsulfamic :acid.

To 600 pounds of water there were added 63.5 pounds of3-hydroxy-2-naphth-o-toluidide and 16 pounds of sodium hydroxide byweight). The mixture was warmed to about 75 C. and stirred to solution,then cooled to C.

To the diazo solution there was added 2.5 pounds of a polyoxyethylatedfatty alcohol known as Emulphor ON.

The coupler solution was then added to the diazo solu- 4 tion, withstirring, while maintaining the temperature below 20 C. After thecoupling reaction was complete the product was filtered, washed withwater and dried. The dye product has the formula:

on CONH Gate Five ounces of the dye was dissolved in 1 gallon of waterand then thickened to a padding consistency with 0.2 ounce of Keltex gum(gum tragacanth) and 0.1 ounce of Leonil SA (anionicnaphthalenesulfonate dispersing agent). A 5 /2 x 18 inch piece of Dacronpolyester fiber (poly-condensate of terephthalic acid with ethyleneglycol) was padded with the above dye at F., dried, and .then subjectedto 425 F. for 1 /2 minutes. The material was soaped for 5 minutes at theboil, rinsed and dried. A strong bright orange dyeing of good build-up,and exceptional light fastness, sublimation, dry cleaning and crockfastness was obtained.

Thus having described the invention it is manifest that obviousmodifications and variations thereof will occur to those skilled in theart without departing from the spirit and scope of the invention.Therefore, it is intended that all such modifications and variations beincluded within the scope of the appended claims insofar as the state ofthe art permits.

1. A method for coloring a polyester fiber a strong, bright orange colorto produce a dyeing characterized by fastness to light, Washing and drycleaning, crocking and sublimation which comprises impregnating at atemperature of from 140 F. to 180 F. a polyester fiber with an aqueouscomposition containing a dyestuff of the formula:

drying the fiber and subjecting the fiber to heat at a temperature offrom 390 F. to 440 F. for 'a period of time sufiicient to develop fullcolor.

2. The method according to claim 1 further characterized in that thedried, impregnated fiber is subjected to heat at a temperature of from390 F. to 440 F. for a period of from one-half to two minutes.

References Cited UNITED STATES PATENTS 2,663,613 12/1953 Gibson 8-4 X3,238,189 3/ 1966 May et a1. 8-55 X FOREIGN PATENTS 809,221 2/-1959Great Britain.

NORMAN G. TOHCHIN, Primary Examiner.

T. J. HERBERT, Assistant Examiner.

